There are a variety of known methods for fabricating an ink jet recording sheet, or print media having a glossy surface for near-photographic prints. One example is directed to a single layer coated paper that uses alumina in the ink-receiving layer. The commercial paper coated with alumina on paper base can provide excellent gloss and absorbing capacity, but it has poor scratch resistance, poor air fading resistance and suffers cockle when the paper is wet.
A second example is directed to a coating with alumina base layer and a colloidal silica top layer. The design helped the scratch resistance but has lower lightfastness, poor air fading resistance, and bleed in humid conditions all associated with alumina pigments. Another important pigment is silica. Coatings based on silica pigment have better porosity, are less hygroscopic and have better air and light fading resistance.
A third example is directed to products with a single layer comprising porous (amorphous) silica pigments. However, the product has low gloss, typically below 20 gloss units at 20 degrees incident angle (as measured).
Finally, an ink jet-receiving sheet using anionic spherical silica coated on anionic amorphous porous silica has been developed. The design provides excellent image quality and gloss, but the water fastness and humid fastness performance are not as good as one might like, because the black pigment used has a negative charge, and therefore, has no mordant power to the dye molecules, which are usually anionic in the color inks.
Thus, while anionic SiO2 is available, it does not provide both good gloss and porosity at the same time as a single layer. A two-layer combination (ink receiving layer) of anionic amorphous SiO2 (bottom layer) and anionic spherical SiO2 (top layer) provides good gloss; however, the waterfastness, the humid fastness, and the affinity of the receiving layer to dye (anionic) are not good. As mentioned above, a two-layer combination comprises Al2O3 (bottom layer) and SiO2 (top layer), which also is deficient, as noted above.
A need remains for a print medium having a coating thereon that evidences acceptable gloss, but avoids all, or at least most, of the problems of the prior art.